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Exercise

Advanced subquery

You can also nest multiple subqueries to answer even more specific questions.

In this exercise, for each of the six continents listed in 2015, you'll identify which country had the maximum inflation rate (and how high it was) using multiple subqueries. The table result of your query in Task 3 should look something like the following, where anything between < > will be filled in with appropriate values:

+------------+---------------+-------------------+
| name       | continent     | inflation_rate    |
|------------+---------------+-------------------|
| <country1> | North America | <max_inflation1>  |
| <country2> | Africa        | <max_inflation2>  |
| <country3> | Oceania       | <max_inflation3>  |
| <country4> | Europe        | <max_inflation4>  |
| <country5> | South America | <max_inflation5>  |
| <country6> | Asia          | <max_inflation6>  |
+------------+---------------+-------------------+

Again, there are multiple ways to get to this solution using only joins, but the focus here is on showing you an introduction into advanced subqueries.

Instructions 1/3
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  • 2
  • 3
  • Now it's time to append the second part's query to the first part's query using AND and IN to obtain the name of the country, its continent, and the maximum inflation rate for each continent in 2015!
  • For the sake of practice, change all joining conditions to use ON instead of USING (based upon the same column, code).
  • Revisit the sample output in the assignment text at the beginning of the exercise to see how this matches up.
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